sprite: add resolution, optimize matches()

dist/palette.json

@@ -1,6 +1,7 @@
 {
   "baseurl": "/sprites",
   "sections": 4,
+  "resolution": 128,
   "sprites": [
     {
       "url": "/01.png",

src/sprite.ts

@@ -42,6 +42,8 @@ export interface IPaletteData {
      * (as in the four edges of a quadratic tile).
      */
     sections: number,
+    /** horizontal and vertical resolution of all sprites, in pixels */
+    resolution: number,
     /** Array of all tile prototypes. */
     sprites: ISpriteData[],
 }
@@ -66,19 +68,33 @@ export class Sprite {
             .catch(e => console.error(e));
     }
 
-    public matches(ownDir: Direction, other: Sprite): boolean {
-        if (other.sections !== this.sections) {
+    public matches(ownEdge: Direction, other: Sprite, otherEdge: Direction): boolean {
+        const sections = this.sections;
+        if (other.sections !== sections) {
             return false;
         }
 
-        const ownStart = ownDir * this.sections;
+        const getStart = (edge: Direction) => {
+            let start = edge * sections;
+            if (edge >= 2) {
+                start += sections - 1;
+            }
+            return start;
+        };
+        let ownPos = getStart(ownEdge);
+        let otherPos = getStart(otherEdge);
 
-        const otherDir: Direction = (ownDir + 2) % 4;
-        const otherStart = otherDir * other.sections;
+        const ownDir = ownEdge < 2 ? 1 : -1;
+        const otherDir = otherEdge < 2 ? 1 : -1;
+        for (let n = 0; n < sections; n++) {
+            if (this.edges[ownPos] !== other.edges[otherPos]) {
+                return false;
+            }
+            ownPos += ownDir;
+            otherPos += otherDir;
+        }
 
-        let ownEdge = this.edges.slice(ownStart, ownStart + this.sections);
-        let otherEdge = other.edges.slice(otherStart, otherStart + other.sections);
-        return !ownEdge.some((v, i) => otherEdge[other.sections - i - 1] !== v);
+        return true;
     }
 
     /**
@@ -126,20 +142,23 @@ export const enum Direction {
 export class Palette {
     private readonly sections: number;
     public readonly sprites: Sprite[];
+    public readonly resolution: number;
 
     public constructor(proto: IPaletteData) {
         this.sections = proto.sections;
-        const tiles = [];
-        for (let tile of proto.sprites) {
-            tiles.push(new Sprite(proto.sections, proto.baseurl, tile));
+        const sprites = [];
+        for (let s of proto.sprites) {
+            sprites.push(new Sprite(proto.sections, proto.baseurl, s));
         }
-        this.sprites = tiles;
+        this.sprites = sprites;
+        this.resolution = proto.resolution;
     }
 }
 
 const PALETTE_SCHEMA: JSONSchema = {
     baseurl: "string",
     sections: "number",
+    resolution: "number",
     sprites: [{
         url: "string",
         edges: ["number"],